Conventionally, an electronic control unit, which is exposed to a high-pressure water flow in washing a vehicle, such as an electronic control unit that is arranged in an engine room of a vehicle and performs control of an engine is well known. For example, as described in JP-A-2008-55981 and JP-A-2009-6808, a waterproof housing includes a ventilation hole and a sheet-like filter for covering the ventilation hole.
In an electronic control unit (waterproof device) described in JP-A-2008-55981, a filter membrane is attached to an outer surface of a cover (waterproof housing) by an adhesive sheet having multiple micropores so that a ventilation hole (through-hole) is closed. The adhesive sheet and the filter membrane correspond to the above-described filter.
In an electronic control unit (waterproof device) described in JP-A-2009-6808, a recess is formed in an upper surface side of a case (waterproof housing) having a ventilation hole (through-hole) to surround the ventilation hole, and a sheet-like breathing filter (filter) is attached to a bottom surface of the recess to cover the ventilation hole (through-hole).
However, in the configurations described in JP-A-2008-55981 and JP-A-2009-6808, a high-pressure water flow at an unchanged impetus may be directly poured on the sheet-like filter attached to the waterproof housing, as described above. Thus, there is a problem that the filter is easily peeled off.
If the filter is peeled off, water or the like enters into the waterproof housing, and thus, a short-circuit may occur in a circuit board or the like, or an electronic device may break down.